US10317455B2ActiveUtilityA1
Apparatus and method for monitoring an electrical insulation for an onboard power supply system of a vehicle
Est. expiryMar 17, 2034(~7.6 yrs left)· nominal 20-yr term from priority
Inventors:Lars Schmelzer
B60L 3/0069G01R 31/005G01R 27/025G01R 31/1227G01R 31/025B60Y 2200/91G01R 19/165G01R 31/006B60Y 2200/92G01R 19/2513G01R 31/52
26
PatentIndex Score
0
Cited by
33
References
10
Claims
Abstract
A device for monitoring an electrical insulation in a vehicle electrical system comprises a voltage source that generates DC voltages and a determining unit, configured to determine an insulation resistance between the vehicle electrical system and ground and from current measurement values of at least two current measuring units and from the first and second voltage values.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1. An apparatus for monitoring an electrical insulation for an onboard power supply system of a vehicle, the apparatus comprising:
a power source configured to generate a first DC voltage having a first voltage value and a second DC voltage having a second voltage value;
an electrical connection point via which a positive power supply line of the onboard power supply system and a negative power supply line of the onboard power supply system are electrically connected to one another;
a first current path between the positive power supply line and the electrical connection point;
a second current path between the negative power supply line and the electrical connection point;
a third current path between the electrical connection point and the power source;
at least two of the following three current measuring units:
a first current measuring unit in the first current path for measuring a first current flowing through the first current path;
a second current measuring unit in the second current path for measuring a second current flowing through the second current path;
a third current measuring unit in the third current path for measuring a third current flowing through the third current path;
an ascertainment unit that is electrically connected to the respective signal output of the at least two of the three current measuring units via signal inputs;
wherein the ascertainment unit is configured to ascertain from measured current values from the at least two of the three current measuring units and also the first and the second voltage value an insulation resistance between the onboard power supply system and electrical ground;
wherein the first voltage value is about 50 to about 60 volts and the second voltage value is about −60 to about −50 volts.
2. The apparatus as claimed in claim 1 , wherein the apparatus comprises all three current measuring units and wherein the ascertainment unit is electrically connected to the respective signal output of the three current measuring units via the signal inputs.
3. The apparatus as claimed in claim 1 , wherein the apparatus has, in the first current path, a first resistor for limiting the first and the third current, and has, in the second current path, a second resistor for limiting the second and the third current.
4. The apparatus of claim 1 , wherein the apparatus has, in the first current path, a first controllable switch configured to break or make electrical connection in the first current path and has, in the second current path, a second controllable switch configured to break or make electrical connection in the second current path.
5. A method for monitoring an electrical insulation for an onboard power supply system of a vehicle, the method comprising:
wiring a power source between electrical ground and an electrical connection point via which a positive power supply line of the onboard power supply system and a negative power supply line of the onboard power supply system are electrically connected to one another;
generating a first DC voltage having a first voltage value, by the power source;
measuring a first current value of a first and a second current, wherein the first and the second current each flow through one of the following three current paths under the effect of the first DC voltage:
a first current path between the positive power supply line and the electrical connection point;
a second current path between the negative power supply line and the electrical connection point;
a third current path between the electrical connection point and the power source;
generating a second DC voltage having a second voltage value by the power source;
measuring a second current value flowing through the respective current path in each case under the effect of the second DC voltage; and
determining an insulation resistance between the onboard power supply system and electrical ground from the first and the second voltage value and also the first and the second measured current values;
wherein, the insulation resistance is computed as the quotient of the difference between the first and the second voltage values corrected by respective voltage values dropped across respective resistors of the respective current paths and the difference between the first and the second current values.
6. The method of claim 5 , wherein the insulation resistance is determined from the following equation:
R_ISO
=
(
Uq
1
-
Ia
1
·
Ra
)
+
(
Uq
1
-
Ib
1
·
Rb
)
-
(
Uq
2
-
Ia
2
·
Ra
)
-
(
Uq
2
-
Ib
2
·
Ra
)
n
·
(
(
Ia
1
-
Ia
2
)
+
(
Ib
1
-
Ib
2
)
)
where
n is a numerical coefficient,
Ra and Rb are resistance values in the respective current paths (Pa, Pb) through which the respective currents (Ia, Ib) flow under the effect of the first and second DC voltages.
7. The method of claim 6 , wherein
measuring a first current value provides a first operating voltage value of the operating voltage of the onboard power supply system to be measured;
measuring a second current provides a second operating voltage value of the operating voltage to be measured;
wherein the first and the second operating voltage values are compared with one another;
wherein in the event of a discrepancy between the first and the second operating voltage values:
the first measured current values are rejected;
a third DC voltage having a third voltage value is generated by the power source; and
a respective third measured current value of the first and the second current flowing through the respective current path in each case under the effect of the third DC voltage is measured; and
wherein the step of determining an insulation resistance further provides for the insulation resistance to be ascertained from the second and the third voltage values and also the second and the third measured current values.
8. The method of claim 7 wherein:
the step of measuring a first current further provides for a first operating voltage value of the operating voltage to be measured;
the step of measuring a second current further provides for a second operating voltage value of the operating voltage to be measured;
wherein the first and the second operating voltage value are compared with one another, wherein in the event of a discrepancy between the first and the second operating voltage value, a correction factor is ascertained, and
the step of determining an insultation resistance further provides for the insulation resistance to be corrected by the correction factor.
9. The method of claim 8 , wherein the correction factor is read from a previously ascertained correction factor table on the basis of the discrepancy between the first and the second operating voltage values.
10. The method of claim 5 , wherein
the step of measuring a first current value further provides for not only the first measured current values of the first and the second current but also a first measured current value of a third current flowing through the remaining current path in the three current paths under the effect of the first DC voltage to be measured;
the step of measuring a second current further provides for not only the second measured current values of the first and the second current but also a second measured current value of the third current flowing through the remaining current path under the effect of the second DC voltage to be measured;
wherein the first and the second measured current value of the third current are used to check the accuracy of the ascertained insulation resistance.Join the waitlist — get patent alerts
Track US10317455B2 — get alerts on status changes and closely related new filings.
We store only your email — no account needed. See our privacy policy.